Bath trap seal depth

16 Jul 2009
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United Kingdom
When a bath is discharged in to a stack with its own 1.5inch inch waste pipe. What is the minimum trap seal depth is it 75mm. I know mcalpine do a 50mm trap depth. The the shallow ones that are 38mm seal or 19mm seal for discharge in to a hooper. Is the 50mm trap depth OK for this purpose?
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Bath trap depth seal is 50mm minimum when discharging into a stack. Shallow bath traps can be used if bath empties into a gulley or hopper. The shallow trap can be easily pulled by negative pressure in the stack from other appliances discharging such as toilets flushing. I see loads of shallow traps discharging into stacks though.

Sink and basin trap seal minimum is 75mm. Baths get away with a shallower seal because baths are essentially flat bottomed and the last bit of water through the plughole as the bath empties will be moving quite slowly and the trap seal is less likely to be lost through momentum or siphonage.
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